The present invention relates to light-stabilized organic polymers.
More specifically, the present invention relates to organic polymers light-stabilized by the addition, to said organic polymers, of an effective quantity of one or more compounds belonging to the group of enamines consisting of derivatives of xcex2-keto-esters, or xcex2-keto-amides or 1,3-diketones with primary or secondary aliphatic or aromatic amines, carrying at least one sterically hindered amine group in the molecule.
It is known that organic polymers undergo degradation over a period of time as a result of exposure to atmospheric agents, and mainly to ultraviolet radiation, and they also easily undergo thermoxidative degradation during processing and transformation processes.
This degradation causes a deterioration in the physical characteristics of organic polymers such as, for example, a reduction in the impact strenght and flexure as well as alterations in the optical properties of the end-article.
Stabilizing compounds are usually introduced into organic polymers to prevent the above degradation.
The Applicant has now found that compounds belonging to the group of enamines consisting of derivatives of xcex2-keto-esters, or xcex2-keto-amides or 1,3-diketones with primary or secondary aliphatic or aromatic amines, carrying at least one sterically hindered amine group in the molecule, are capable of stabilizing organic polymers to which they are added improving their resistance to light, in particular, to ultraviolet radiation.
The above compounds are capable of absorbing ultraviolet radiation with a maximum absorption at a wave-length equal to 280 nm. This wave-length has a particularly aggressive action towards organic polymers.
The present invention therefore relates to organic polymers light-stabilized by the addition, to said organic polymers, of an effective quantity of one or more compounds belonging to the group of enamines consisting of derivatives of xcex2-keto-esters, or xcex2-keto-amides or 1,3-diketones with primary or secondary aliphatic or aromatic amines, carrying in the molecule at least one sterically hindered amine group, having general formula (I): 
wherein
m represents an integer from 1 to 3, extremes included;
n represents an integer from 1 to 4, extremes included;
R1 represents a triazine having one or the following general formula (II), (III) or (IV): 
xe2x80x83wherein R5 represents a hydrogen atom; a linear or branched C1-C18 alkyl group; a xe2x80x94NHR6 amine group or a xe2x80x94SR6 group wherein R6 represents a hydrogen atom or a linear or branched C1-C18 alkyl group;
R1 and R2, the same or different, represent a hydrogen atom; a linear or branched C1-C8 alkyl group; a linear or branched C2-C8 alkoxyalkyl group; a C5-C8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C6-C18 aryl group; a C7-C20 arylalkyl or alkylaryl group; a group having general formula (V): 
xe2x80x83wherein R7 represents a hydrogen atom; a linear or branched C1-C18 alkyl group, said alkyl group optionally substituted with a xe2x80x94NHR8 group or an xe2x80x94OR8 group wherein R8 represents a hydrogen atom, a linear or branched C1-C18 alkyl group, or a C6-C18 aryl group; an xe2x80x94OR9 group wherein R9 represents a hydrogen atom, or a linear or branched C1-C18 alkyl group;
or, R1 and R2 considered jointly with the nitrogen atom, represent a C5-C8 heterocyclic group optionally containing a second heteratom selected from oxygen, nitrogen and sulfur;
R3 and R4, the same or different, represent a linear or branched C1-C18 alkyl group; a C6-C18 aryl group; a C7-C20 alkylaryl or arylalkyl group; a linear or branched C1-C8 alkoxyl group;
or, R4 represents a group having general formula (VI): 
xe2x80x83wherein R7 has the same meanings defined above;
or, R4 represents an NR10R11 group wherein R10 and R11, the same or different, represent a hydrogen atom; a linear or branched C1-C18 alkyl group; a linear or branched C2-C8 alkoxyalkyl group; a C5-C8 cycloalkyl group optionally containing a heteroatom selected from oxygen, nitrogen and sulfur; a C6-C15 aryl group; a C7-C20 arylalkyl or alkylaryl group; a triazine having one of the following general formula (II), (III) or (IV): 
wherein R5 has the same meanings defined above; a group having general formula (V); 
wherein R7 has the same meanings defined above;
or, R10 and R11 considered jointly with the nitrogen atom, represent a C5-C8 heterocyclic group optionally containing a second heteroatom selected from oxygen, nitrogen and sulfur;
or R4 represents a group having one of the following general formulae (VII), (VIII) or (IX): 
wherein:
R12 represents a hydrogen atom; or a linear or branched C1-C18 alkyl group;
R13 represents a linear or branched C1-C8 alkyl group; a xe2x80x94COCH2COCH3 group; or a direct bond;
xe2x80x83provided that, when R1 and R2 are different from the group having general formula (V), R4 represents a group having general formula (VI).